Insulator



Dec; 20, 1927. 1,653,436

H. P. LIVERSIDGE INSULATOR Original Filed July 22, 191-3 Patented Dec. 2, i927.

ATET

HORACE P. LIVERSIDGE, 0F BALA, PENNSYLVANIA, ASSIGNOR TO ELECTRICAL DIE- VELOPMENT AND MAGHINE COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A.

CORPORATION.

INSULATOR.

Application filed July 22, 1918, Serial No. 246,056. Renewed June 31., 1927.

A purpose of my invention is to shrink a band or sleeve to the porcelain of an insulator, fashioning it true to .the was of the insulator forsubsequent connection with a top or base, as by co-operating screw threads or other desirable mechanical means.

A further purpose is to use a metal of relatively low melting point for the connecting band, preliminarily leaving the surface to 1 which it is applied unglazed or otherwise giving it a roughened or non-cylindrical contour. I prefer to use a metal having a low coefficient of expansion for the band and to cast the band upon the insulator under pressure, thereby securing more intimate contact or enabling it to be handled at a lower temperature.

Further urposes will appear in the specification and in the claims.

I have preferred to illustrate my invention by but one main form'thereof selecting therefor a form which is practical, eficient and possesses great strength against cantilever and tensile strain and which at the same time well illustrates the principles of my invention.

Fig. 1 is a top plan view of the preferred form of my invention.

Fig. 2 is a combined elevation and vertlcal central section of the construction seen in Fig. 1.

Fig. 3 is an enlarged broken sectlon corresponding to apart of Fig. 2.

Fig. 4 is a broken side elevation of another form of my invention so far as the exterior contour is concerned.

Fig. 5 is a fragmentary section showing amold used in casting.

In the drawings similar numerals represent like parts.

Uniting insulator porcelain parts to metal connections by molten metal presents various difiiculties.

Where the molten metal is poured directly between the parts to be unlted it shrinks radially in its entirety and also locally awa from the outer of these parts, losing the sti ening efiect and strength to be had by firm contact. This I overcome by casting the metal between the insulator and an outer mold which is not the member with which it is to engage finally.

For the highest grade Work the temperatures mustalso be considered. The porcelam cannot be heated very much without reducmg both its mechanical and insulating strength. With metals having a high melting point or which are 'not die-cast there is danger of injury to the porcelain due to the relatively high temperature at which the metal must be cast to avoid chillingand the contact is not the best with the surfaces against which the cast metal is intended to engage.

I find that the best results are attained by casting the metal against the porcelain under pressure, obtaining closer contact and better flow at the temperature selected and permitting the use of a metal having a low coeficient of expansion.

ll have discovered that there is a great ad vantage in placing the metal by which the union is to be made about the porcelain first, before applying the outer member ultimately intended. I prefer to give the molten metal its outer finish or contour by a subsequent operation, finishing it exteriorly true to the axis of the porcelain to fit accurately into the connection by which it is to be united with the bus bars or with the base. I consider that I can more readily make any correction in alinement subsequent to the casting operation than during the setting for it.

The mechanical finish can thus be given to it very accurately, so that the parts can be assembled in place, truing up the bus bars with the base absolutely in whatever position of adjustment as to height the bus bars occupy. This last I have accomplished by threaded connection but obviously it can be done in other ways.

The porcelain insulator body 1 is shown as united to a connecting ring 2. at the top and to the flange 3 of a base 4 at the .bottom through metal bands 5 and 6 which are cast in place between the insulator and split outer molds 7 (Figure 5) preferably under pressure. The bands shrink against the insulator when the metal cools. Pressure during the casting gives good contact and pressure during solidification maintains contact and also gives an effect similar to additional shrinkage. Both are desirable though much of the benefit of my invention can be obtained without the use of pressure. I show a. split spacer 8, used during the casting for the purpose of providing an annular groove at this point.

The two ends of the insulator are suitably roughened or otherwise prepared for receipt of the metal bands 5 and 6 and I have shown grooves 9, 9 for this purpose. Obviously, any roughening would serve, asthe metal will closely conform to the inequalities of surface of the insulator. Leavin these surfaces of the insulator unglaze d, without other roughening has been found to give.

good results.

I select a metal of relatively low melting point for the cast band,-in order that it may not crack or otherwise injure the surface of the insulator. This may be a babbitt, though I preferably use a spelter. harder than babbitt for the purpose. The outer metal form 7 may be heated to add its heat to that of the molten metal where the intended use of the insulator or character of material used for the band permit this additional heat to be applied.

By using pressure during the casting I am enabled to et full contact between the metal of the ban and the inequalities of the porcelain with a speed of action and strengthof support of the insulator otherwise difiicult to obtain.

The best finish for the two shrunk metal bands is by external threads accurately .placed with reference to the true axis of the insulator, as a support or base, as the case may be, can then be placed upon them reliably and quickly in accurate alinement, whatever the distance (i. e. height adjustment) between the two. I prefer to place the threads by aseparate and subsequent operation.

The two metal bands are threaded at 10 and 11 to co-operate with like threads upon the interior of the collar or ring 2 at 12 and the flange of the base at 13. The base is also united to the insulator by a pin 14 and insulating cement 15 within a central cavity 16. The interior of the cavity 16 and the exterior of the pin are both shown as grooved, as at 17 and 18.

The collar or ring 2 is shown as having threaded engagement with the lower frame member 19 of a bus bar clamp, which is apertured at suitable points for bolts 20. An.

upper frame member 21 completes the clamp for bar 22. The frame member 19 can be screwed into the collar to different distances for different heights of bus bar adjustment, and may be locked in position by screws 23, bearing upon a washer 24.

In assembly, an'elastic or resilient washer 25 is placed between the ring 2 or base flange, as the case may be, and an adjoining shoulder of the insulator body, so that the ring or base flangedoes not come in direct contact with the orcelain which is firmly sup ported at its e ge in an axial direction by the resilient connection thus formed.

This insulator cannot get out of alinement since it cannot be put together in any other way than the way intended and the alinement is maintained, whatever the height at which the bus bar clamp is set.

The insulating surface is divided into a flash-over flange 26 at the top and a lower creeping surface 27 of much greater length, axially. I prefer to locate the flash-over flan e within approximately the upper thirdof the axial length of the exposed insulator forming the lower two thirds as a relatively smooth creeping surface, free from abrupt changes of direction which would weaken it against cantilever strains and might also cause unbalanced stresses during the firing. The lower portion of the insulator should be nearly Vertical forming angles in vertical planes not'greater than 30 with the axis of the insulator.

The flash-over flange may be used with or wit hout ahead 28, as the slight grooving for such a bead at this point is not serious.

The surface at 27 preferably tapers at about the same rate as the leverage from the bus bars increases so as to give commensurate mechanical strength along with a de-' sirable insulating surface. In order to avoid danger of leakage at the bottom and also to support the outer edge of the bottom of the insulator by the base for mechanical reasons, I make the diameter of the base flange approximate that of the bottom of the exposed part of the insulator and get the best support where, as in Figure 4 the lower body portion is lar est at the bottom and its outer surface su stantially merges with the outer surface of the base flange.

It will be evident that a part of the benefit of my invention may be obtained by using parts only of the structure disclosed herein and that the disclosure made will enable others skilled in the art to apply the invention in many other forms than that shown.

It will be evident that the construction shown eliminates unequal firing strains and the sharp corners and deep flutings which are so frequent a cause of mechanical failure of insulators. It gives a large flash-over surface and a lar e creeping surface and at the same time distributes the material of the main part of the body so as to secure a maximum of strength from the material utilized.

Having thus described my invention, what I claim as new and desire to secure by Letters Patentis:

1. A porcelain insulator in combination with a band of soft metal shrunk upon it tightly gripping its periphery at one end and having an exposed outer surface finished for attachment of supporting parts.

2. A porcelain insulator having its outer Surface roughened at an end and its adjoinvingsurface smooth in combination with a.

band of low-fusing-point metal tightly engaging the roughened portion and a support for the insulator surrounding the band.

neaaase 5 threads upon the outside of the collars and connecting fittings threaded upon the collars for support of the insulator and for support of the conductor therefrom.

4. In an insulator, a body portion, an ex- 10 teriorly' threaded metal band of soft metal tightly engagin the exterior of the top of the insulator'an conformin to its inequalities and a connection for t e conductor to be held, terminating at its lower end in an a 15 interiorly threaded sleeve adapted to be screwed upon said band and thereby retained in position and adjusted in height.

5. An integral ost insulator, in combination'. with bands 0 soft metal tightly engaging the top, and bottom and a base and cap surrounding the'said'bands of metal and removably secured thereto.

6. In an insulator, a bodyportion substantially cylindrical at the top and bottom, soft metal bands rigidly engaging the cylindrical portions and cyhn'drical base and cap members removably engaging the soft metal bands and one of them adjustable thereon to adjust the effective height of the insulator.

7. An integral insulator havin a soft metal band rigidly secured to the Insulator body at each end, one of them abutting the insulator body axially, a cylindrical base member engaging the soft metal band and a cylindrical cap member adjustable upon the soft metal band-at the top to adjust the effective height of the insulator.

HORACE P. LIVERSIDGE. 

